Antichamber

i can't understand how to fall down.. i did already take the other path and i did fall down one time in the wrong side the one with only the door but i can not manage to fall down again.. how do you do it?

For jumping across, you don't actually need any blocks to fall down, you can actually strafe slightly and hit the wall. For the puzzle at the bottom, your goal is actually to move the blocks OFF the lasers. You can do this by taking away a block, and moving another block into it's place before it re-appears, thus creating 1 block instead of two. There's also another way to do this, if you take away the blocks that are blocking the lasers, it is possible to get through the door just before they come back. (I did it this way, so I know it's possible.)